"A tracking warrant also allowed the SPVM to activate the GPS chip in the iPhone to know exactly where Lagacé was, admitted two investigators in charge of the file."

How is this possible? You carrier can activate your GPS chip? And then the GPS sends its coordinates to your carrier?

By sending binary SMSs. There are multiple classes of SMS, including binary messages through which operators can access and change data directly on your SIM. Since that's also your crypto chip, yeah ...

TLDR: https://www.contextis.com/resources/blog/binary-sms-old-back...

If you have a few days: http://www.tamps.cinvestav.mx/~vjsosa/clases/redes/Mobile%20...

Edit: You might find them referenced as silent SMSs, because you never see any indication of receiving it.